Nicosulfuron and Primisulfuron Root Uptake, Translocation, and Inhibition of Acetolactate Synthase in Sugarbeet (Beta vulgaris)

Abstract

Field studies have shown primisulfuron to be more injurious to sugarbeet than nicosulfuron 1 and 2 yr after herbicide application. Experiments were initiated to determine if primisulfuron is more injurious to sugarbeet grown in a nutrient culture and if the difference in sugarbeet response is a result of greater uptake, translocation, or acetolactate synthase (ALS) site sensitivity with primisulfuron. Concentrations of primisulfuron and nicosulfuron that reduced sugarbeet growth by 50% were 1.9 and 8.9 μg ai L−1, respectively, at pH 6.5. The pH of the nutrient solution did not influence sugarbeet response to either herbicide. Uptake of primisulfuron was greater (3%) than that of nicosulfuron (1%). Translocation (expressed as a percent of uptake) of nicosulfuron was more rapid than primisulfuron. Fifty-seven percent of the absorbed nicosulfuron translocated out of the root during the 12-h pulse period, while an equal concentration of primisulfuron was not translocated out of the root until 48 h after pulsing. The total nicosulfuron translocated after 144 h was half that of primisulfuron. The nutrient solution taken up by sugarbeet in the 12-h pulse period was reduced by 41% in the presence of either herbicide compared to the untreated control. The ALS enzyme was a minimum of 15 times more sensitive to primisulfuron compared to nicosulfuron which may account for greater sugarbeet response to primisulfuron.

Absorption, translocation, and metabolism of halosulfuron and trifloxysulfuron in green kyllinga (Kyllinga brevifolia) and false-green kyllinga (K. gracillima)

“…Burnet et al (1994) elucidated two mechanisms of resistance to sulfonylurea herbicides within one population of rigid ryegrassthat of enhanced detoxification through metabolism of the parent compound and a less-sensitive ALS enzyme. In addition to decreased sensitivity within weed species, Novosel and Renner (1995) attributed greater phytotoxicity to sugarbeet with primisulfuron compared with nicosulfuron to the differential affinity to the ALS-enzyme.…”

Injury and Yield Effects on Crops Grown in CGA 152005-Treated Soil1

“…Primisulfuron persisted in soil and injured sugarbeet (Beta vulgaris L.) 1 yr after application (Chomas and Kells 1993), and sugarbeet was 15 times more sensitive to primisulfuron than nicosulfuron soil residues (Novosel and Renner 1995). Primisulfuron injured rotational crops including sugarbeet as long as 3 yr after application (Dexter and Luecke 1993).…”